1. Field of the Invention
The present invention relates to an ion implantation apparatus and a control method for an ion implantation apparatus.
2. Description of the Related Art
In a semiconductor production process, a process of implanting ions into a semiconductor wafer (hereinafter, it may be referred to as an “ion implantation process”) is generally performed for the purpose of changing the conductivity and/or the crystalline structure of the semiconductor and the like. An apparatus that is used in the ion implantation process is called an ion implantation apparatus and has a function of forming an ion beam by generating ions using an ion source and accelerating the generated ions and a function of transporting the ion beam to a vacuum processing chamber and irradiating a wafer with the ion beam inside the vacuum processing chamber. In addition, in the ion implantation apparatus, a device that supplies a wafer before the implantation of ions to the vacuum processing chamber and takes out the wafer to which the ions have been implanted (hereinafter, it may be referred to as a “wafer conveyance device”) is disposed.
The wafer conveyance device includes a load lock chamber used for bringing a wafer placed under the atmospheric pressure into the vacuum processing chamber. After bringing a wafer into the load lock chamber under the atmospheric pressure, the wafer conveyance device evacuates the load lock chamber, causes the load lock chamber that is in the vacuum state and the vacuum processing chamber to communicate with each other, and brings the wafer into the vacuum processing chamber. Since a time required for bringing the wafer into is highly influenced by an evacuation time of the load lock chamber, the processing capability of wafer conveyance can be increased by arranging a plurality of load lock chambers. For example, as a wafer conveyance device of which the conveyance capability is increased, a configuration is employed in which two load lock chambers are arranged on a right side and a left side and an intermediate conveyance chamber is arranged between the load lock chambers and the a vacuum processing chamber.
In addition, as a wafer conveyance device of which the conveyance capability is further increased, a configuration is also proposed in which each of a right load lock chamber and a left load lock chamber is configured to be a two stage type, and thus four load lock chambers in total are provided. In the conveyance device, a two-stage-type wafer conveyance robot and/or a two-stage-type alignment mechanism is provided corresponding to the two-stage-type load lock chamber.
The conveyance capability can be increased by employing the two-stage-type load lock chamber. However, since each of the load lock chamber, the wafer conveyance robot and the alignment mechanism is configured to be a two stage type, structure of each device is complex. Therefore, production cost or maintenance cost is increased compared to the case of a one stage type. Inventors of the present invention are considered that there is room to improve wafer conveyance capability by enhancing efficiency of a conveyance process between a wafer container and a load lock chamber even in a case where a one-stage-type right load lock chamber and a one-stage-type left load lock chamber are used.